Parent Company Condensed Financial Information - Statements of Net Income (Details) - USD ($) $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2019	[1]	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Total Interest Income	$ 82,457		$ 79,813	$ 79,624	$ 78,590	$ 76,589	$ 73,627	$ 71,581	$ 68,029	$ 320,484	$ 289,826	$ 260,642
Interest expense on long-term debt										1,831	1,129	463
Income tax benefit	$ 5,091		$ 4,743	$ 5,070	$ 4,222	$ 4,952	$ 2,876	$ 4,010	$ 6,007	19,126	17,845	46,437
Net Income										98,234	105,334	72,968
Parent Company
Condensed Income Statements, Captions [Line Items]
Dividends from subsidiaries										59,490	44,988	36,169
Investment income										1	24	22
Total Interest Income										59,491	45,012	36,191
Interest expense on long-term debt										1,285	1,149	955
Other expenses										4,325	3,988	3,801
Total Expense										5,610	5,137	4,756
Income before income tax and undistributed net income of subsidiaries										53,881	39,875	31,435
Income tax benefit										(1,189)	(1,093)	(1,596)
Income before undistributed net income of subsidiaries										55,070	40,968	33,031
Equity in undistributed net income (distribution in excess of net income) of bank subsidiary										42,683	68,385	40,877
Equity in undistributed net income (distribution in excess of net income) of nonbank subsidiaries										481	(4,019)	(940)
Net Income										$ 98,234	$ 105,334	$ 72,968

[1] The DNB Merger is included in our consolidated financial statements beginning on December 1, 2019.